ALBERT

Description: Energy management in its most comprehensive sense encompasses economic, technical, environmental, and political problems. The present evaluation of prospects notes that opportunities for energy conservation are widespread, in such fields as building air conditioning, transportation, electrical appliances, and industrial processes. Further conservation is expected to be achieved through a combination of technology development and economics; the latter factor must not be unduly influenced by political measures that shield consumers from the true cost of energy.

Description: This paper presents the results of a series of total and spectral solar irradiance measurements made at ground surface (Table Mountain Facility, Calif., altitude 2.18 km). The spectral irradiance data are presented for the 0.3-3.0-micron spectral region for air mass 1.5.

Description: Background information and exercises are provided to: (1) establish or expand understanding of the concepts, methods, and terminology of computer processing of image producing data; (2) develop insight into the advantages of computer based image processing compared with the photointerpretation approach for processing, classifying, interpreting, and applying remote sensing data; (3) foster a broad perspective on the principal of the main techniques for image enhancement, pattern recognition, and thematic classification; (4) appreciate the pros and cons of batch and interactive modes of image analysis; (5) examine and evaluate some specific computer generated products for subscenes in Pennsylvania and New Jersey; and (6) interrelate these particular examples of output with more theoretical explanations of computer processing strategies and procedures.

Description: The High Resoltuion Spectrograph (HRS) in conjunction with the Space Telescope (ST), extends ultraviolet astronomical spectroscopy to higher spectra, spatial, and time resolutions than previously achieved, as well as to fainter and more distant celestial objects. Other significant advances inherent in the instrument are high photometric accuracy and efficient operation via exposure meter control and real time rejection of bad data. These capabilities are provided to accomplish the scientific programs of the HRS investigation definition team, which concern the interstellar medium, stellar winds, and evolutionary aspects of stellar atmosphere studies; the determination of chemical abundances relevant to stellar evolution; the investigation of quasars and Seyfert galaxy nuclei; and the analysis of the atmospheres of solar system objects, including comets.

Description: A proposal for a multi-institutional investigation of the processes involved in the growth and maintenance of high level extended clouds is presented. Mapping of variability of the cloud and of its radiative characteristics in terms of the meteorological environment of the cloud; performance of case studies involving observation of the cloud microphysics and radiation characteristics; and investigation of the processes responsible for the generation, maintenance, and dissipation of the cloud system are recommended. Both modeling and monitoring activities are considered. The specific research projects which the author proposes to carry out are described. Suggestions for the administrative organization of the total effort are presented.

Description: The interplay of the various physical processes involved in the formation, maintenance, and decay of middle and upper tropospheric stratiform clouds is discussed. Ice phase fair weather cloud forms are considered. Simulations of cirriform clouds which attempt to incorporate the physical processes in an interactive manner were performed. A two dimensional time dependent Eulerian numerical model, which incorporates all of the important physical processes in a simplified way, is employed to investigate the role of these processes in the evolution of a cloud in an isolated atmospheric layer. Physical parameters considered are the eddy viscosity and the thermal, water vapor, and ice water eddy diffusivities.

Description: The papers in this section include: 1)'Wind Derivation from Geostationary Satellites'; 2) 'The Operational Processing of Wind Estimates from Cloud Motions: Past, Present, and Future'; 3) 'Intercomparision of SMS Wind Sets: A Study Using Rapid Scan Imagery'; 4) 'Mesoscale Wind Fields for a Severe Storm Situation Determined from SMS Cloud Observations'; 5) 'Moisture Convergence Using Satellite-Derived Wind Fields: A Severe Local Storm Case Study'

Description: There are different levels of helicopter noise prediction which may be appropriate at various stages in the design process. In the early preliminary design stages, when available information is usually limited to parameters such as gross weight, tip speed, forward speed, rotor radius, and possibly number of blades, one is limited to purely empirically based methodology. As the design progresses, and airfoil blade planforms and twists are defined, predictions of airloads, vortex paths, and compressibility effects may permit application of more analytically based sound pressure level prediction methods. At the present stage of development of first principle prediction methodology, however, the designer may still find it necessary to supplement such analyses with modifications based on empirical experience. Various causes and parameters of helicopter noise were identified and discussed from the standpoint of prediction. Rotational noise, blade-vortex interaction noise, thickness noise, broadband noise, and flyover noise were considered. A modular computer program for helicopter noise prediction (HELNOP) was described briefly. Wind tunnel models as useful tools in predicting full scale helicopter noise were also discussed.

Description: A KC-135A aircraft equipped with wing tip winglets was flight tested to demonstrate and validate the potential performance gain of the winglet concept as predicted from analytical and wind tunnel data. Flight data were obtained at cruise conditions for Mach numbers of 0.70, 0.75, and 0.80 at a nominal altitude of 36,000 ft. and winglet configurations of 15 deg cant/-4 deg incidence, 0 deg cant/-4 deg incidence, and baseline. For the Mach numbers tested the data show that the addition of winglets did not affect the lifting characteristics of the wing. However, both winglet configurations showed a drag reduction over the baseline configuration, with the best winglet configuration being the 15 deg cant/-4 deg incidence configuration. This drag reduction due to winglets also increased with increasing lift coefficient. It was also shown that a small difference exists between the 15 deg cant/-4 deg incidence flight and wind tunnel predicted data. This difference was attributed to the pillowing of the winglet skins in flight which would decrease the winglet performance.

Description: A joint NASA/USAF program was conducted to accomplish the following objectives: (1) evaluate the benefits that could be achieved from the application of winglets to KC-135 aircraft; and (2) determine the ability of wind tunnel tests and analytical analysis to predict winglet characteristics. The program included wind-tunnel development of a test winglet configuration; analytical predictions of the changes to the aircraft resulting from the application of the test winglet; and finally, flight tests of the developed configuration. Pressure distribution, loads, stability and control, buffet, fuel mileage, and flutter data were obtained to fulfill the objectives of the program.

Description: A full-scale winglet flight test on a KC-135 airplane with an upper winglet was conducted. Data were taken at Mach numbers from 0.70 to 0.82 at altitudes from 34,000 feet to 39,000 feet at stabilized flight conditions for wing/winglet configurations of basic wing tip, 15/-4 deg, 15/-2 deg, and 0/-4 deg winglet cant/incidence. An analysis of selected pressure distribution and data showed that with the basic wing tip, the flight and wind tunnel wing pressure distribution data showed good agreement. With winglets installed, the effects on the wing pressure distribution were mainly near the tip. Also, the flight and wind tunnel winglet pressure distributions had some significant differences primarily due to the oilcanning in flight. However, in general, the agreement was good. For the winglet cant and incidence configuration presented, the incidence had the largest effect on the winglet pressure distributions. The incremental flight wing deflection data showed that the semispan wind tunnel model did a reasonable job of simulating the aeroelastic effects at the wing tip. The flight loads data showed good agreement with predictions at the design point and also substantiated the predicted structural penalty (load increase) of the 15 deg cant/-2 deg incidence winglet configuration.

Description: A model that explains the flat-spot power loss phenomenon is presented. Evidence suggests that the effect is due to localized metallurgical interactions between the silicon substrate and the contact metallization. These reactions are shown to result in localized regions in which the P-N junction is destroyed and replaced with a metal semiconductor-like interface. The effects of thermal treatment, crystallographic orientation, junction depth, and metallization are shown along with a method of preventing the effect through the suppression of vacancy formation at the free surface of the contact metallization. Data indicating the effectiveness of a TiN diffusion barrier in preventing the effect are also given.

Description: The significance of the Space Telescope for the advancement of astronomy and astrophysics is described. The current state of knowledge in astronomy and cosmology is summarized and unanswered questions in those fields discussed. The rapid evolution of modern astronomy and the need for systematic observations are stressed.

Description: Astrometry with the Space Telescope (ST) is performed using one of the fine guidance sensors (FGS). The FGS, which is based on a pair of Koester's prism interferometers, one for each axis, is capable of measuring the position of one object relative to another with an accuracy of 0.002 arcseconds. Astrometric Data Reduction Software (ADRS) available to the astrometric user of ST is described. The kinds of problems the space telescope astrometry team plans to investigate using ST are discussed.

Description: A wide site of potential astronomical and solar system scientific studies using the wide field planetary camera on space telescope are described. The expected performance of the camera as it approaches final assembly and testing is also detailed.

Description: The role of the European Coordinating Facility is described. European participation in the Space Telescope Science Institute and the relation of Space Telescope to ground-based astronomy in Europe are discussed.

Description: A comprehensive set of measurements about the orbiter environment are provided by the plasma diagnostics package (PDP). Ion and electron particle densities, energies, and spatial distribution functions; ion mass for identification of particular molecular ion species; and magnetic fields, electric fields and electromagnetic waves over a broad frequency range are studied. Shuttle environmental measurements will be made both on the pallet and, by use of the remote manipulator system (RMS), the PDP will be maneuvered in and external to the bay area to continue environmental measurements and to carry on a joint plasma experiment with the Utah State University fast-pulsed electron generator. Results of orbiter environment EMI measurements and S-band field strengths as well as preliminary results from wake search operations indicating wake boundary identifiers are reported.

Description: The Earth radiation budget experiment (ERBE) software development approach is described. An iterative development approach was adopted which provides for three releases or versions of the processing system, each of increasing levels of complexity and solidity. The final release of the system will be used to process the flight data. The major phases for each iterative release consist of specifications developed in concert with the science team, preliminary design, subsystem reviews, coding, subsystem code walkthroughs, system testing, system documentation, and project status review.

Description: The correlation of outgassing to the stability of the damping properties of polymer materials to be used in spacecraft structures is discussed. A test series was devised to obtain basic information from off-the-shelf damping materials. The test results could be considered as a guideline toward the application of these materials. Eight materials were selected to form a representative cross section of those polymers having both ready availability as commercial damping materials and desirable properties. A table indicates the temperatures at which peak damping occurs at 1 Hz and the type of beam specimen used in the vacuum exposure tests. These materials as a group cover the temperature range of -85 C to 38 C.

Description: Both separate and combined wind tunnel and vibration shaker tests were conducted on two structural panels representative of the Shuttle orbiter in the NASA LaRC 8-foot transonic pressure tunnel to determine the effects of combined loads on the thermal protection system (TPS). The primary objective of this test was to provide a combined full-scale load environment and realistic time history of the dynamic pressures, Mach numbers (through transonic), and dynamic structural responses of these panels. The panels were selected from orbiter locations where interactive load sources such as aerodynamic shock waves, turbulent boundary layers, strut-induced vorticity, and substrate deformation combined to provide high bonding loads between the TPS and the orbiter structure. The test panels were highly instrumented with static and dynamic pressure gages, accelerometers, deflectometers, strain gages, Schileren and high speed photography, and special instrumentation necessary to determine TPS/structure interface loads and tile motions. Two test specimens of each orbiter panel were utilized. Both were high-fidelity representations of the selected orbiter location.

Description: Results of wind-tunnel and acoustic tests to investigate buffet loads on Shuttle Thermal-Protection-System (TPS) tiles are given. Also described is the application of these results to the prediction of tile buffet loads for the first shuttle flight into orbit. The wind-tunnel tests of tiles were conducted at transonic and supersonic Mach numbers simulating flow regions on the Orbiter where shock waves and boundary-layer separations occur. The acoustic tests were conducted in a progressive wave tube at an overall sound pressure level (OASPL) approximately equal to the maximum OASPL measured during the wind-tunnel tests in a region of flow separation. The STS-1 buffet load predictions yielded peak tile stresses due to buffeting that were as much as 20 percent of the total stress for the design-load case when a shock wave was on a tile.

Description: The dynamic and static analysis methods used to model the nonlinear structural behavior of the Shuttle Orbiter's tile/pad thermal protection system are discussed. The structural evaluation of the tile/pad system is complicated by the nonlinear stiffening, hysteresis and viscosity exhibited by the pad material. Application of the analysis to square tiles subject to sinusoidal and random excitation is presented along with appropriate test data. Correlation is considered good. In order to treat the stress analysis of thousands of individual tiles, a nonlinear static analysis was developed which utilizes equivalent static loads derived from the dynamic environment. Tensile stress at the bondline is examined in thousands of unique tiles.

Description: The Shuttle tile ascent environments are discussed and the procedures used to convert these environments into tile loads are outlined. Testing which was performed to quantify or verify the loads are discussed, along with the load combination rationale which was used. The discussion of the ascent environment is limited to the transonic/supersonic portion of the mission since mechanical design loads occur during this time, and to specific regions of the vehicle, in particular those regions in which undensified critical (black) tiles are located.

Description: The thermal protection system (TPS) of the Space Shuttle Orbiter is described as well as the results of dynamic reponse studies conducted in support of the efforts to certify the TPS for flight. The ceramic Thermal Protection System consists of ceramic tiles bonded to felt pads which are in turn bonded to the Orbiter substructure to protect the aluminum substructure from the heat of reentry.

Description: The unique space shuttle vehicle size, weight, and configuration gave rise to problems in determining vibration requirements and in verifying structural integrity for anticipated mission environments. The applications of large-scale vibration testing played a prominent part in qualifying the shuttle for its intended missions. Severe vibration excitation from rocket engines, aerodynamic noise, and onboard equipment are expected on each shuttle flight. Scale-model wind tunnel and rocket firing tests, as well as full-size rocket engine tests were relied on to define the random forcing functions. The determination of structural response to these environments is described as well as evaluations of measured flight data and comparison with predicted design and test criteria.

Description: A computerized data bank system was developed for utilization of large amounts of vibration and acoustic data to formulate component random vibration design and test criteria. This system consists of a computer, graphics tablet, and a dry-silver hard copier which are all desk-top type hardware and occupy minimal space. The data bank contains data from the Saturn V and Titan III flight and static test programs. The vibration and acoustic data are stored in the form of power spectral density and one-third octave band plots over the frequency range from 20 to 2000 Hz. The data was stored by digitizing each spectral plot by tracing with the graphics tablet. The digitized data was statistically analyzed and the resulting 97.5% probability levels were stored on tape along with the appropriate structural parameters. Standard extrapolation procedures were programmed for prediction of component random vibration test criteria for new launch vehicle and payload configurations. This automated vibroacoustic data bank system greatly enhances the speed and accuracy of formulating vibration test criteria. In the future, the data bank will be expanded to include all data acquired from the space shuttle flight test program.

Description: One nemesis of the structural dynamist is the tedious task of reviewing large quantities of data. This data, obtained from various types of instrumentation, may be represented by oscillogram records, root-mean-squared (rms) time histories, power spectral densities, shock spectra, 1/3 octave band analyses, and various statistical distributions. In an attempt to reduce the laborious task of manually reviewing all of the space shuttle orbiter wideband frequency-modulated (FM) analog data, an automated processing system was developed to perform the screening process based upon predefined or predicted threshold criteria.

Description: Recovery of the space shuttle solid rocket boosters required development of a heavy duty large decelerator subsystem. Successful recovery of the first launch pair of boosters demonstrated the adequacy of the design. Flight data consisting of accelerometers and parachute attach point loads provide a basis for evaluation of the decelerator subsystem performance. These results are summarized and compared to preflight predictions.

Description: Solid rocket booster cavity collapse flight measurements included external pressures on the motor case and aft skirt, internal motor case pressures, accelerometers located in the forward skirt, mid-body area, and aft skirt, as well as strain gages located on the skin of the motor case. This flight data yielded applied pressure longitudinal and circumferential distributions which compare well with model test predictions. The internal motor case ullage pressure, which is below atmospheric due to the rapid cooling of the hot internal gas, was more severe (lower) than anticipated due to the ullage gas being hotter than predicted. The structural dynamic response characteristics were as expected. Structural ring and wall damage are detailed and are considered to be attributable to the direct application of cavity collapse pressure combined with the structurally destabilizing, low internal motor case pressure.

Description: Transpiration cooling is treated and then full coverage discrete hole injection for three injection orientations. Spacings with pitch to diameter ratios of 5 and 10 are discussed. The array is staggered, with the transverse pitch and the streamwise pitch the same. Results are presented in terms of the Stanton number using the heat transfer coefficient defined in terms of the difference between the wall temperature and the free stream temperature. Two values of Stanton number are provided for each situation: one with the injectant at wall temperature, and the other with the injectant at free stream temperature. These two values are equivalent to knowing the heat transfer coefficient and the adiabatic effectiveness. The heat transfer coefficient thus defined is used with the actual wall temperature to and the actual gas temperature to calculate the heat load. The principle of superposition thus invoked is valid exactly when the governing equations are linear.

Description: Charts relating to helicopter noise reduction design efforts are given. Information regarding priorities, design guidelines, design margins, risks, noise prediction, derivative trends, design impact, and cost impact is given.

Description: High speed compressibility noise and vortex interaction noise, which are aerodynamically generated noise sources, were investigated. Noise generating mechanisms were identified. Linear and nonlinear theory were compared and are in agreement with data on amplitude and wave forms. The interaction area between the acoustic planform and blade/vortex interaction lines are examined.

Description: Calculated engine core noise levels, based on NASA Lewis prediction procedures, for five representative helicopter engines are compared with measured total helicopter noise levels and ICAO helicopter noise certification requirements. Comparisons are made for level flyover and approach procedures. The measured noise levels are generally significantly greater than those predicted for the core noise levels, except for the Sikorsky S-61 and S-64 helicopters. However, the predicted engine core noise levels are generally at or within 3 dB of the ICAO noise rules. Consequently, helicopter engine core noise can be a significant contributor to the overall helicopter noise signature.

Description: The history and methodology of aerodynamic noise reduction in rotary wing aircraft are presented. Thickness noise during hover tests and blade vortex interaction noise are determined and predicted through the use of a variety of computer codes. The use of test facilities and scale models for data acquisition are discussed.

Description: Noise reduction is mostly limited to light helicopters whose noise signature is dominated by their tail rotors. It is primarily hardware oriented. Well known noise reduction techniques such as reduction of rotor speeds with an accompanying increase in solidity to maintain performance, engine noise reduction with the use of exhaust mufflers, and acoustic blanketing of transmission and engine compartment are used. The concept of blade phasing as a means of reducing tail rotor noise is also used. Engine noise (exhaust noise), power train noise and airframe noise becomes important at low rotor tip speeds and means must be found to reduce these noise sources if further noise reductions are desired. The use of a special test rig aids in isolating the various noise sources and arriving at the penalties (performance or payload) involved in quieting them. Significant noise reduction are achieved for the light helicopter with minimum performance or weight penalties because of the dominance of a single noise source (the tail rotor).

Description: The development of technology to aid in the design of advanced rotor blades to improve both aerodynamic and acoustic performance is discussed. The development of advanced computer codes to calculate the subsonic and transonic flow field about rotor blades and to model such high noise producing phenomena as shock waves and blade/vortex interaction is examined. The codes are verified by comparison with experimental data. Making the codes available to industry and to provide some training for the industrial users is emphasized.

Description: The purpose of this presentation is to give a general strategy for rotorcraft noise prediction. This strategy is expressed through a modular software system design rather than theoretical analysis of the aerocoustic phenomena. The crucial design choices in a software system design are the module interface definitions. An interface is the data that are passed from one module to another. A module takes data from one (input) interface and transforms it, through a prediction method, to another (output) interface. In system design, the method is less important than the interface. The two types of methods available may be braodly classified as empirical or analytical, although no method is purely one or the other. These two general approaches will be compared as they apply to rotorcraft noise prediction.

Description: Various parameters of helicopter rotor noise were considered. Impulsive noise, flow regions of a helicopter rotor, noise prediction, aspect ratio, blade tip shape and speed, and blade-vortex interaction noise were among the topics addressed. Recommendations were also given.

Description: Boeing Vertol Model 234, CH-47D and 347 tandem rotor helicopters demonstrate noise levels that comply with the overall noise standard requirements. The helicopters achieve these noise levels because they are, by design, free of impulsive noise in level flight and climb. Avoiding an impulsive noise signature is achieved by developing and applying configuration design criteria that eliminate blade vortex intersections and recognize advancing blade tip noise limitations in high speed forward flight. Airfoil design, rotor separation and rotor tipspeed selection all contribute to the noise control. Compliance with the approach element of the standards is marginal at best. The approach problem is not appreciably alleviated by reduced tipspeed and airfoil design. Since it is a single rotor phenomenon, it is not alleviated by rotor separation in the tandem configuration. Tip shapes may provide the answer, but to date this approach has not led to a satisfactory solution.

Description: The tools currently available for acoustic design risk reduction and problem solving are limited in accuracy and do not encompass all design parameters. Assuming available technology, designing helicopters to confidently meet noise limits as were proposed by the FAA and were now adopted by ICAO will result in significant design compromises.

Description: Images characteristics of geographic regions other than the northeastern part of the United States are presented for interpretation. Pre- and post-eruption imagery of Mt. St. Helens volcano serves to demonstrate the advantages of thermal infrared sensing, and the potential for developing a timely, decision oriented thematic map to be used in solving drought-related problems in Upper Volta is examined to show the applicability of satellite remote sensing in all geographic areas.

Description: Functional requirements of helicopter noise reduction are discussed from the work environment point by view, i.e., what conditions must exist before the designer can take aim, without too many restraints, at reducing noise, community demand for noise reduction, regulatory requirements, competition, and penalties are among the topics discussed.

Description: The engineering management strategy involved in designing helicopters to meet a noise requirement is discussed. A different perspective is given on how designs were accomplished in the past, how a new design would be carried out today, and how knowledge gained through acoustics R&D will have two important effects. It will lead to invention of quieter features to be incorporated, and it will improve the ability to predict accurately the noise levels of new designs before they are built. Each of these effects changes the basic design process.

Description: The aerodynamic prediction methodology which is needed for rotor noise calculations is presented. Airloads and wakes, dynamic stall, compressible flow, and random loads are reviewed. The aerodynamics/acoustics interface is defined when the noise or measurements are considered. The classical approach involving a distinct separation of aerodynamic sources and acoustic propagation is the basis of most rotor noise calculations. Aeroacoustics of rotors involve unique features which are not encountered in other aerodynamic problems of rotors: (1) acoustics problems ultimately require only an order of magnitude estimate of the sound pressure field, consequently remarkably good noise predictions are obtained from very simple aerodynamic analyses; (2) aeroacoustics introduce an interest in the higher frequency aerodynamics, the deterministic aerodynamic phenomena are still low frequency, however, the high frequency noise comes from the acoustic propagation; and (3) the aerodynamic phenomena on rotors that are only of interest due to the noise they produce, are the random aerodynamic pressures on the blades.

Description: It is important for industry and NASA to assess the status of acoustic design technology for predicting and controlling helicopter external noise in order for a meaningful research program to be formulated which will address this problem. The prediction methodologies available to the designer and the acoustic engineer are three-fold. First is what has been described as a first principle analysis. This analysis approach attempts to remove any empiricism from the analysis process and deals with a theoretical mechanism approach to predicting the noise. The second approach attempts to combine first principle methodology (when available) with empirical data to formulate source predictors which can be combined to predict vehicle levels. The third is an empirical analysis, which attempts to generalize measured trends into a vehicle noise prediction method. This paper will briefly address each.

Description: The geostationary and polar satellites comprising the current operational system are discussed. The data acquisition capabilities of both satellite types and their complementary functions are reviewed. The advanced very high resolution radiometer on the TIROS N satellites is particularly addressed along with the imaging and atmospheric sounding instrumentation aboard the GOES satellites. The dissemination of the satellite data to the prospective users is also discussed.

Description: Some of the reusable heat shielding materials used to protect the Space Shuttles, their manufacturing processes, properties, and applications are discussed. Emphases is upon ceramic materials. Space Shuttle Orbiter tiles are discussed.

Description: A long-range program in support of the aerospace industry aimed at reducing the use of strategic materials in gas turbine engines is discussed. The program, which is called COSAM (Conservation of Strategic Aerospace Materials), has three general objectives. The first objective is to contribute basic scientific understanding to the turbine engine technology bank so that our national security is not jeopardized if our strategic material supply lines are disrupted. The second objective is to help reduce the dependence of United States military and civilian gas turbine engines on worldwide supply and price fluctuations in regard to strategic materials. The third objective is, through research, to contribute to the United States position of preeminence in the world gas turbine engine markets by minimizing the acquisition costs and optimizing the performance of gas turbine engines. Three major research thrusts are planned: strategic element substitution; advanced processing concepts; and alternate material identification. Results from research and any required supporting technology will give industry the materials technology options it needs to make tradeoffs in material properties for critical components against the cost and availability impacts related to their strategic metal content.

Description: Polymer synthesis programs involve the development of Novel thermoplastics, pseudothermoplastics, and thermosets. These systems are prepared to elucidate structure-property relationships involving thermal capabilities, toughness, processability and environmental stability. Easily processable polyimides, solvent-resistant polysulfones and polyphenylquinoxalines, and tougher high and intermediate temperature polymers were developed. Characterization efforts included high pressure liquid chromatography methodology, the development of toughness tests for fiber reinforced composites, a study of electrical properties of metal ion filled polyimides, and a study of the mutagenicity of aromatic diamines. Also the mechanism of cure/degradation of experimental polymers was studied by rheology, mechanical behavior, separation techniques and spectroscopy. The degradative crosslinking of alkyl-containing polyimides, the separation and identification of crosslinked phenylquinoxalines, the rheological behavior of hot-melt polyimides, and the elucidation of the cure of norbornene endcapped imides were also studied.

Description: Stratospheric limb radiance profiles versus altitude of closest approach of the line of sight to the Earth's surface have been measured before and after the Mount St. Helens eruptions by means of photographs taken from a Sun-oriented balloon gondola floating above 35 km altitude over France. Preliminary data were reported for flights in October 1979 and in May and June 1980. The radiance integrated along the line of sight as in-situ radiance (R) can be derived taking into account absorption by ozone and air. The onion peeling inversion method was used to derive the vertical radiance (R) profiles respectively. The values of R were determined in the solar azimuth. The solar elevation angles are chosen larger for the backscattering observation than for the forward scattering observation to deal with as similar illumination conditions as possible despite the Earth's sphericity.

Description: Twenty filter sampling flights of the NASA Lewis F-106 aircraft were conducted in the Great Lakes region between June 4 and August 8, 1980, following the major eruption of Mount St. Helens, Washington on May 18. The IPC-1478 filters were exposed over an altitude range spanning the local tropopause. Quarter sections were analyzed for sulfate and nitrate by ion chromatography and selected samples were analyzed for chloride by selective ion electrode. Trace elements were searched by X-ray fluorescence analysis. A filter sample taken above the tropopause on June 5 indicated a sulfate level of 50 times the baseline measurements. Subsequent measurements over a period of 2 months showed an initial dropoff and formation of a persistent layer of sulfate above the tropopause with a concentration of 10 to 18 times previously measured background-levels. Concentrations of nitrate above the tropopause exhibited considerable variability and some enhancement compared with previously measured concentration levels. It is suggested that the source of the nitrate may also be volcanic as evidenced by its temporal relationship to the sulfate concentration changes. Based on the null results of X-ray fluorescence measurements, there is no evidence of ash particle concentrations greater than 3.4 microns g/cubic m persisting in the layer above the tropopause after the second transit of the cloud.

Description: Microscopical investigation of volcanic ash collected from ground stations during Mount St. Helens eruptions reveal a distinctive bimodel size distribution with high concentrations of particle ranges at (1) 200-100 microns and (2) 20-0.1 microns. Close examination of individual particles shows that most larger ones are solidified magma particles of porous pumice with numerous gas bubbles in the interior and the smaller ones are all glassy fragments without any detectable gas bubbles. Elemental analysis demonstrates that the fine fragments all have a composition similar to that of the larger pumice particles. Laboratory experiments suggest that the formation of the fine fragments is by bursting of glassy bubbles from a partially solidified surface of a crystallizing molten magma particle. The production of gas bubbles is due to the release of absorbed gases in molten magma particles when solubility decreases during phase transition. Diffusion cloud chamber experiments strongly indicate that sub-micron volcanic fragments are highly hygroscopic and extremely active as cloud condensation nuclei. Ice crystals also are evidently formed on those fragments in a supercooled (-20 C) cloud chamber. It has been reported that charge generation from ocean volcanic eruptions is due to contact of molten lava with sea water. This seems to be insufficient to explain the observed rapid and intense lightning activities over Mount St. Helens eruptions. Therefore, a hypothesis is presented here that highly electrically charged fine solid fragments are ejected by bursting of gas bubbles from the surface of a crystallizing molten magma particles.

Description: The direct solar radiation transmission record at Mauna Loa, dating from 1958 to the present, revealed with remarkable precision the presence of stratospheric aerosol from volcanic activity. This record can be used to quantify the intensity of the stratospheric volcanic aerosol perturbation following a significant eruption in reference to the Agung event in 1963. The Mount St. Helens' stratospheric cloud was first detected by lidar at 18 km over Mauna Loa on 17 July. The atmospheric transmission was seen to decrease slightly after that time, but only a few tenths of 1 percent. Although it is still fairly early to draw a definite conclusion on the ultimate magnitude of the Mount St. Helens stratospheric aerosol from the Mauna Loa results, it can be stated that the stratospheric aerosol optical depth presently observed is comparable with that observed from Fuego which erupted in 1974. At Boulder, Colorado, the atmospheric debris from Mount St. Helens was observed by lidar on a number of occasions. Also, observations of the diffuse, total and direct transmission of solar radiation were made on June 3 and 4. The latter set of observations is useful for deriving information on the scattering properties of the volcanic cloud. The lidar and solar radiation data are presented and some of their special features are discussed.

Description: Samples of stratospheric aerosols collected with U-2 aircraft for several months following the first three major eruptions of Mount St. Helens were analyzed for ash and liquid acid content. Ash grain sizes and compositions vary depending on collection altitude, location within the drifting cloud, and days following their injection. s computers Size distributions of ash particles vary with altitude. Generally small particles are depleted more rapidly at low altitudes (12 km) than at higher altitudes (17-18 km). Although samples collected 1 day after the first eruption of May 18, 1980, were dry, flow marks on the aircraft indicated parts of the cloud contained heavy acid concentrations. Indeed, all other samples obtained within 1 to 4 days after later eruptions (May 25 and June 12, 1980) were covered with copious amounts of liquid acid. Proportions of liquid to ash varied considerably depending on sampling location and cloud age. Because the acid-coated ash globules were large, they rapidly fell from the stratosphere until, by late June 1980, only a residue of acid droplets remained. Size distributions and concentrations of these droplets varied considerably.

Description: Increased applications of automation technology identified as necessary for NASA to carry out its missions within the constraints of future funding and available physical resources are described. A concept for a Remote Orbital Servicing System (ROSS) based on present teleoperator and robotics technology is presented. A single servicer design compatible with three specified spacecraft, capable of performing service to the same extent as manned extravehicular activity, controlled from a ground control station, and using currently available technology is conceptualized.

Description: The simulation program associated with a key piece of support equipment to be used to service satellites directly from the Shuttle is assessed. The Open Cherry Picker (OCP) is a manned platform mounted at the end of the remote manipulator system (RMS) and is used to enhance extra vehicular activities (EVA). The results of simulations performed on the Grumman Large Amplitude Space Simulator (LASS) and at the JSC Water Immersion Facility are summarized.

Description: The concept of manned and unmanned proximity modules (POM) to assist the Orbiter in retrieval, servicing, and emergency operations of orbiting payloads is discussed. An unmanned POM, capable of examining or capturing and returning to the Orbiter large satellites which are station-keeping at distances up to one kilometer from the Orbiter, is presented and its design features defined. Also presented is the concept of a manned POM which is capable of capturing and maneuvering smaller payloads in or about the Orbiter payload bay. The manned POM also serves as a free flying work station used to support satellite servicing and provide a back-up to Orbiter situations when the remote manipulator is inoperative.

Description: Shortly after the 18 May eruption, a series of airborne lidar flights were made over the Eastern United States. During the same period, ground-based systems were activated throughout the world. The available worldwide lidar data is put together in a consistent set. These data show the dispersion of material at different altitudes during the early global circuits. The material in the lower stratosphere and upper troposphere was very patchy in horizontal extent with backscattering ratio values over the east coast of the United States greater than 100 at the ruby wavelength of 0.6943. Two wavelength ratios and depolarization values for the material in the lower stratosphere (12 to 18 km) appear to have returned to the pre-18 May values within a month after the eruption and this indicated a rapid conversion to spherical shapes and normal indices of refraction. The material above 20 km moved slowly westward while most of the ejecta moved eastward at various speeds and directions which varied considerably with altitude. The westward material was detected first by the Japanese lidar system and then subsequently by the European and American ground-based systems. It circuited the globe in about 60 days. An airborne lidar flight in early September across the continental United States showed the layers to have homogenized considerably one broad layer between about 14 and 21 km peaking at 18 to 19 km and another more intermittent thin layer between 21 and 22 km. The ruby peak backscattering ratio of the broad layer was between 1.3 and 1.5.

Description: The 1980 eruptions of Mount St. Helens in southeast Washington resulted in a pronounced effect on the surface and ground water resources of the state. In response to the volcanic activity, the U.S. Geological Survey intensified statewide surface and ground water sampling programs to determine the nature and magnitude of the volcanic-induced variations. Streams to the east of Mount St. Helens received the major ash fallout. Chemical effects were best noted in smaller streams sampled 60 to 70 miles northeast of Mount St. Helens. The chemical variations observed were pronounced but short lived. Sulfate and chloride increases in anionic composition were prevalent immediately following the eruption; however, the original bicarbonate predominance was again attained within several days. Suspended iron and aluminum concentrations were similarly elevated during the period of greatest ash deposition (highest turbidity); however, the dissolved concentrations remained relatively constant. Depressions of pH were minor and short lived. Streams draining to the south, tributaries to the Columbia river, showed little observable changes in water chemistry. Streams draining to the west (Toutle river and its tributaries) were compositionally affected by the various volcanic activities. Chloride and sulfate anion percentage exceeded the bicarbonate percentage up to one month following the eruption period. Streams and lakes sampled in the immediate vicinity of Mount St. Helens, in addition to trace metals, contained organic compounds derived from decomposing wood buried in the debris deposits. This organic material may constitute a significant source of organic compounds to surface and ground water for some time to come.

Description: The benefits-to-cost ratio of satellite remote sensing, both as a substitute for conventional methods of monitoring and assessing resources, and as a supplement to these methods is examined using a model which analyzes the cost of aerial photography versus satellite scanner for producing and interpreting an image of the Earth's surface sized to LANDSAT dimensions. Examples of cost savings are tabulated for ground surveys, aerial photos, and LANDSAT. Possible additional benefits from LANDSAT D are assessed. The way in which satellites fit into more comprehensive models for resources management is discussed. It is shown that remote sensing is but one essential component in a complex system that aggregates technical. Socioeconomics, political, cultural, and other factors in the human decision process.

Description: Computer processing facilitates extraction of information from every pixel by executing a variety of functional operations, called processed algorithms, in general or specialized routines. The best results are obtained when data from more than one multispectral band are used together. Multivariate tatistical analysis, computer tape characteristics, processing modes, and a choice of systems (batch or interactive) are discussed. The major operations in computer processing elaborated include: preprocessing, enhancement, effects of rationing, and classification. Techniques for multisource data correlation are considered with emphasis on geobased systems.

Description: Learning objectives include: (1) developing an understanding of the implications of the term "near surface observations"; (2) associating the appearance of large ground features as seen in satellite imagery with their appearance as seen from the ground; (3) grasping criteria and procedures for selecting training sites on the ground for use in supervised classification; (4) running through an example of training site selection; (5) becoming familiar with several methods of accuracy assessment; (6) becoming aware of the approach and value of making supporting measurements of the spectral and physical properties of materials on the ground and from aircraft; (7) taking note of the different types of instruments used in making specific ground measurements; and (8) appreciating the rationale underlying laboratory and field studies on or near the Earth's surface for the purpose of developing new sensor systems.

Description: Learning objectives include: (1) developing a facility for applying conventional techniques of photointerpretation to small scale (satellite) imager; (2) promoting the ability to locate, identify, and interpret small natural and man made surface features in a LANDSAT image; (3) using supporting imagery, such as aerial and space photography, to conduct specific applications analyses; (4) learning to apply change detection techniques to recognize and explain transient and temporal events in individual or seasonal imagery; (5) producing photointerpretation maps that define major surface units, themes, or classes; (6) classifying or analyzing a scene for specific discipline applications in geology, agriculture, forestry, hyrology, coastal wetlands, and environmental pollution; and (7) evaluating both advantages and shortcomings in relying on the photointerpretive approach (rather than computer based analytical approach) for extracting information from LANDSAT data.

Description: Activities are provided for: (1) developing insight into the way in which the LANDSAT MSS produces multispectral data; (2) promoting understanding of what a "pixel" means in a LANDSAT image and the implications of the term "mixed pixel"; (3) explaining the concept of spectral signatures; (4) deriving a simple signature for a class or feature by analysis: of the four band images; (5) understanding the production of false color composites; (6) appreciating the use of color additive techniques; (7) preparing Diazo images; and (8) making quick visual identifications of major land cover types by their characteristic gray tones or colors in LANDSAT images.

Description: Learning objectives of the activities provided include: (1) reading the annotation of a LANDSAT image; (2) becoming acquainted with the characteristics of 1:1,000,000 scale transparencies and prints of MSS images; (3) noting the general information visible in LANDSAT photo products; (4) observing changes of appearance of any ground feature or class in the black and white images made from the four MSS bands and the characteristic color of each class in color composites; (5) determining the degree to which a LANDSAT image meets map accuracy standards and can be fitted to map projections; (6) assessing the effects of LANDSAT enlargements and scale changes and of the limitations of satellite resolution relative to aerial photos; (7) observing the influence of time of acquisition (season) on a scene; (8) getting a feel for image quality as dependent on processing and photoreproduction; (9) appreciating the characteristics of the RBV and thermal band imagery obtained from LANDSAT-3; and (10) becoming familiar with certain attributes of adjacent LANDSAT images which permit them to be joined in mosaics and to be viewed in stereo.

Description: Programs for the development and operation of meteorological satellites from the TIROS 1 satellite and the establishment of NASA through the 1960's are described. The technical problems confronted in the development of the early satellite systems are discussed in addition to issues in international involvement and program support. The TIROS and Nimbus series satellites are primarily addressed.

Description: The adhesion, friction, and wear properties of materials are reviewed and some of the factors influencing these properties are discussed. The forms of lubrication and types of lubricants will also be discussed.

Description: Research at NASA Langley's Materials Characterization Instrumentation Section has followed the philosophy of improving the science base of nondestructive evaluation and advancing the state of the art of quantitative interpretability of physical measurements of materials. Details of several R&D programs choosen to highlight the last several years are given. Applications of these technologies are presented in the area of stress measurement, characterization of metal heat treatment, and evaluation of material internal structure. A second focus of the program is on quantitative transducers/measurements that have resulted in better data in irregular inhomogeneous materials such as composites. Examples are presented of new capabilities resulting from these advances that include fatigue and impact damage evaluation.

Description: Research on three classes of materials that show potential for allowing significant increases in operating temperatures in gas turbine engines is discussed. Monolithic ceramics, ceramic matrix composites, and carbon-carbon composites are discussed. Sintering, hot pressing, and densification are discussed.

Description: Tephra and aerosols from the May 18, 1980 eruption of Mount St. Helens, Washington were sampled in the lower stratosphere with a WB-57F aircraft. The main body of the plume was intercepted over western Kansas on May 20, 48 hours after the eruption, at an altitude of 15.2 km. Concentrations on filter samples were 26 ng of SO4(-2) of air and 579 ng of ash/g of air. Angular glass pyroclasts ranged in size from 0.5 to 10 microns, with a mean grain of 2 microns. Samples collected at altitudes of 16.7 and 12.5 km had only traces of SO4(-2) and ash. A second flight was flown, 72 hours after the eruption, on May 21. From north Texas to central Wyoming, at an altitude of 15.2 km less than 0.5 to 38 ng of ash/g of air and 1.0 to 2.2 ng of SO4(-2)/g of air were sampled. At an altitude of 18.3 km, from central Wyoming to NW New Mexico, the plume density and character were variable.

Description: The SAGE satellite system was used to make measurements on the optical extinction produced by stratospheric aerosols from the Mount St. Helens eruption. Two periods of observation were analyzed. In the first period (May 21 to 31, 1980), SAGE moved southward from latitude 60 N, and crossed the United States approximately one week after the May 18th eruption. Enhancements in stratospheric extinction were confined to latitudes between about 55 N and 25 N and longitudes between 10 W and 140 W. Individual layers were observed up to altitudes of 23 km. The geographical location of these layers corresponded closely to that expected on the basis of high-altitude meteorological data. During June and much of July, SAGE was, by reason of its geographical position and other orbital characteristics, unable to make further measurements on the northern hemisphere. Between July 19th and August 12th a second southward pass over the northern hemisphere occurred and further observations were made. The volcanic aerosol in the stratosphere was now found to be widely distributed over the hemisphere, the maximum concentrations being north of 50 N. The aerosol showed considerable inhomogeneity and had reached as far south as 15 N but little, if any, had crossed the equator into the southern hemisphere. Individual layers at different heights were still distinguishable. The total stratospheric aerosol loading on this occasion appeared to be greater than in May and corresponded to an increase in global stratospheric mass of between 50 and 100 percent.

Description: Servicing economics for LANDSAT are examined. The following objectives of the multimission modular spacecraft are outlined: retrieval; multimission capability; standard flight support system; standard hardware; repair and refurbishment on orbit; instrument replacement; standard ground support system; and standard software.

Description: A conceptual definition of an appropriate berthing technique and a prototype design of an automatic umbilical system suitable for use with payloads carried by the Space Shuttle are presented. A four-element berthing system is described. This concept consists of a set of four remote manipulator system (RMS)-type end-effector capture/tie-down devices on the power system and corresponding RMS-type grapple fittings on the payload. In operation, the RMS maneuvers the payload to a position where the four grapple fittings can be snared within the end-effectors and then secured to the power system. The concept takes advantage of mechanisms and operating techniques developed for attaching the RMS to a payload. Although the umbilical installation is attached to the docking interface structure, its operation is independent and it must comply with a set of primary requirements specified by Marshall Space Flight Center (MSFC), which is presented.

Description: Orbiter-based service equipment needs/usage are identified by considering a broad spectrum of on-orbit operational scenarios associated with three primary mission events: initial launch, revisits, and Earth return. Nominal and alternate modes of operation, contingency situations (as remote manipulator system inoperative), and Orbiter close proximity operations are included. Satellite classes considered are direct delivery and servicing of the orbiter, low Earth orbiter/propulsion, sorties and DOD, geosatellites, and planetary and other satellites.

Description: Payloads are secured in the orbiter payload bay by the payload retention system or are equipped with their own unique retention systems. The orbiter payload retention mechanisms provide structural attachments for each payload by using four or five attachment points to secure the payload within the orbiter payload bay during all phases of the orbiter mission. The payload retention system (PRS) is an electromechanical system that provides standarized payload carrier attachment fittings to accommodate up to five payloads for each orbiter flight. The mechanisms are able to function under either l-g or zero-g conditions. Payload berthing or deberthing on orbit is accomplished by utilizing the remote manipulator system (RMS). The retention mechanisms provide the capability for either vertical or horizontal payload installation or removal. The payload support points are selected to minimize point torsional, bending, and radial loads imparted to the payloads. In addition to the remotely controlled latching system, the passive system used for nondeployable payloads performs the same function as the RMS except it provides fixed attachments to the orbiter.

Description: Numerous balloon soundings of the aerosol and condensation nuclei (CN) concentrations were made over Laramie, Wyoming following the eruption of Mount St. Helens in May of 1980. On several occasions the volatility of the particles was tested. In addition, special instrumentation was used to observe the evolution of particle size after the eruption. The particles in the initial cloud were relatively large and nonvolatile. In a relatively short time, however, the aerosol began showing a dominant volatile component. Although there were probably no CN in the original cloud due to the expected very short coagulation life time, high concentrations of unusually small CN particles were observed about a month after the eruption. By the end of September the CN profiles and associated particle size were practically back to normal. At present the aerosol particles show about a three times larger concentration than before the eruption, most of the new material being in a layer centered around 19 km. The net effect of the more recent series of eruptions during the last half of October 1980 seems to be negligible.

Description: The handling and positioning aid which (HPA) provides a wide range of adjustable work stations both inboard and outboard of the cargo bay is discussed. It can assist with berthing and docking, it is robust, stiff, has a simple control system, and is modular. An articulated arm version of HPA employed in a typical servicing mission is shown. Mounted on a base frame that spans the Orbiter cargo bay, the 6 m arm is long enough to hold the satellite being serviced and keep its solar array clear of the Orbiter radiators. By adjusting the length and angle of the support platform mast, and rotating the tip of the HPA arm, almost every item on the satellite can be reached. Spares and change-out units can be brought to and from the work site by the RMS, which is controlled from the aft flight deck. The fore and aft position of the base frame can be changed between Orbiter flights and this, together with the 5 degrees of freedom (DOF) of the long arm, allows work sites to be chosen that meet the clearance, reach and vision requirements of many missions. Flight article activities are shown are shown above the dashed horizontal line and Development Test Article (DTA) work below. Flight article requirements and concepts and the design of the DTA are developed.

Description: Satellite servicing requirements for a continuously manned Space Operations Center (SOC) are discussed. Applications for Orbiter developed service equipment are described, together with representative satellite servicing operations for use on SOC. These services cover the full mission cycle from orbital deployment to on-orbit maintenance/repair and, eventually, removal from orbit. An orbiting base, such as the SOC, can provide many of the same services at less cost than the Space Shuttle transportation system.

Description: Helicopter rotors which are the most complicated noise generators among rotating blade machinery are discussed. The main or the tail rotor can be the dominant source of noise depending on the range of frequencies and the observer position. Significant advances in noise prediction were made. Acoustic analysis is the most successful and general theoretical method to treat the acoustics of helicopter noise. The aerodynamic approach is used to study nonlinear acoustic effects. The results of acoustic analogy depend greatly on the input data.

Description: The purpose of this paper is to examine several aspects of helicopter noise quantification from the standpoint of psychoacoustics. Noise metrics in common use to describe far-field aircraft noise and the noise characteristics which they consider are discussed. Some findings of recent psychoacoustic research related specifically to helicopter noise quantification are presented. Criteria for the accuracy of noise metrics to quantify helicopter noise are discussed. Finally, the prospects for improved metrics and research needed to develop and validate improved metrics or existing metrics are discussed.

Description: Development of future helicopter noise prediction methods requires an accurate experimental data base for correlation studies or assessment of theoretical prediction methods. The aerodynamic and acoustic performance criteria for conducting experimental studies of helicopter noise using existing test facilities were defined. Requirements for ground-based facilities were described in addition to the limitations associated with full scale and model scale studies. Flight testing methods were also evaluated briefly and the restrictions associated with these approaches were cited. Finally, a general evaluation of ground-based and flight testing methods is given. Based on this presentation, future investigators can select the experimental approach best suited for generating a desired data base. Also, facility improvements need to extend the state of the art in helicopter noise experimental studies so that problems can be identified.

Description: Many good small scale facilities are available for rotorcraft noise research. Ames 40 x 80/80 x 120 probably is a good large scale facility for acoustic research of large or small rotorcraft, but the acoustic quality of the modified facility was not yet measured. DNW is probably the best aeroacoustic facility, but may be expensive. Other parameters to consider besides background noise are turbulent level and scale, restructed measurement field, local reflections, and speed range. Advanced measurement techniques improve data quality from any facility.

Description: The primary LANDSAT mission and the system requirements are summarized and pertinent parameters of the spacecraft, its orbit, and payload are tabulated. The history acquisition to entry into the archives for storage and product generation and dissemination is recounted. The LANDSAT D data handling plan is discussed showing requirements for both the MSS CCT and the thematic mapper CCT.

Description: The term remote sensing is defined as well as ideas such as class, pattern, feature, pattern recognition, feature extraction, and theme. The electromagnetic spectrum is examined especially those wavelength regions available to remote sensing. Relevant energy and wave propagation laws are discussed and the characteristics of emitted and reflected radiation and their detection are investigated. The identification of classes by their spectral signatures, the multispectral approach, and the principal types of sensors and platforms used in remote sensing are also considered.

Description: The fabrication of several composite structural articles including DC-10 upper aft rudders, L-1011 vertical fins and composite biomedical appliances are discussed. Innovative composite processing methods are included.

Description: Polymers that provide significant improvements in both efficiency and safety for civilian transport aircraft and military combat aircraft were developed. High strength to weight structures such as carbon fiber composites with long term durability are requirements common to both classes of aircraft. Aircraft safety improvements in fire resistance and crashworthiness of primary and secondary structures are long term objectives for transport aircraft. Void filler ballistic foams, intumescent coatings, and radiation-resistant transparent plastics contribute to vulnerability reduction in combat military aircraft. Low and high velocity impact tolerance, fire resistance, thermal stability, and long term durability of polymers and components are emphasized.

Description: Manufacturers are developing composite versions of structural components on existing aircraft. Development involves testing of various material options before selecting one and then extensive testing to develop an adequate data base of material strength and stiffness properties. Design options are narrowed through analysis and a varied spectrum of development tests on small and large subcomponents. In parallel with this, a suitable production process including economical ply preparation and cure at high temperature and pressure is evolved, tools are designed and fabricated, and full scale components are then manufactured for ground qualification tests, flight tests, and airline service. The various tests include many that are required by the FAA for flight certification, which must precede airline service. Inspection and repair methods to insure adequate maintenance in service are also developed.

Description: An intrusion of volcanic dust occurred over the northern Mojave Desert, one month before the explosive eruption of 18 May 1980. Visibility was reduced to 15 to 30 miles during meteorological conditions that should have yielded a visibility in excess of 100 miles. This intrusion was documented by particle size distributions, scanning electron microscope analysis of Nuclepore filter samples, insolation measurements, observations by Navy and NASA aircraft, and meteorological data. No further incidents have been observed to date because of a lack of simultaneous volcanic activity with the particular wind patterns that existed in April. Therefore, under certain meteorological conditions, the desert of the southwestern United States could be significantly affected by volcanic ash from an eruption of Mount St. Helens.

Description: Routine measurements of ozone and SO2 are made with the Dobson and Brewer spectrophotometers at the Atmospheric Environment Service in Downsview Ontario. On May 20 and 21, 1980, large values of column SO2 were observed with both spectrophotometers at the time of passage of the Mount St. Helens debris. Enhanced SO2 values were first observed at 1800Z on May 20. The maximum column amount of SO2 measured was 0.06 cm at 2200 Z. On May 21, SO2 values slowly decreased from 0.03 cm at 1100 Z cm to 0.01 cm at 2000Z. Typical SO2 amounts due to pollution at the Downsview site are approximately 0.003 to 0.005 cm. At the same time of maximum SO2 enhancement, both Dobson and Brewer spectrophotometers measured a 0.040 cm decrease of total ozone. It is not clear whether the decrease of total ozone was caused by the volcanic cloud or natural ozone variability. Air mass trajectories indicate that the altitude of the debris cloud, which passed over Downsview at the time, was between 10 km and 12 km.

Description: By using the most complete available records of direct beam radiation and volcanic eruptions, an historical analysis of the role of the latter in modulating the former was made. A very simple fallout and dispersion model was applied to the historical chronology of explosive eruptions. The resulting time series explains about 77 percent of the radiation variance, as well as suggests that tropical and subpolar eruptions are more important than mid-latitude eruptions in their impact on the stratospheric aerosol optical depth. The simpler climatic models indicate that past hemispheric temperature can be stimulated very well with volcanic and CO2 inputs and suggest that climate forecasting will also require volcano forecasting. There is some evidence that this is possible some years in advance.

Description: Visible and infrared pictures from two Geostationary Operational Environmental Satellite Systems satellites, in circular orbits at about 19,000 nautical miles, are available continuously at approximately 30 minute intervals. Still pictures and film loops from this system vividly depict the events associated with the May 18, 1980 eruption of Mount St. Helens. The initial explosion, shock wave, and visible horizontal dust distribution during the following week are readily apparent. Meteorological wind and height fields permit the inference of the vertical distribution of volcanic dust as well as explain the atmospheric behavior which caused the visible and nonvisible dust distribution.

Description: Examples of the use of geostationary satellites in meteorology are given. Studies of the rate of change of cumulus clouds and cloud systems and wind parameter determination from cloud motions are reviewed. Computer processed imagery products are also discussed.

Description: The Defense Meteorological Satellite Program is described with particular emphasis on the military applications of METSAT data. Satellite operational support, data processing and image quality requirements are discussed.

Description: A historical overview of the pioneer projects for the development of meteorological satellites is given. In addition, the parallel development of the responsible space agencies and panels is addressed. The Vanguard 2 satellite, the first Earth radiation experiment, and the vidicon equipped TIROS-1 satellite are discussed.

Description: High temperature environmental attack of dollar intensive turbine components reduces turbine efficiency and can limit life. The mechanisms of alloy and coating attack and the effects of interaction with the environment on mechanical behavior. This base of understanding provides the foundation for developing life prediction methods and identifying strategies for controlling attack. Subjects discussed in detail include oxidation and new developments in thermal barrier coating research.

Description: Research on metals processing being conducted to develop improved forming and joining methods with the potential of reducing the weight and cost of future aerospace structures is discussed. The approach followed is to assess the state of the art for fabricating a given structural system, define candidate methods for improving processing, evaluate the merits of each, fabricate and test subelement components, and then scale up the process to demonstrate validity. The development and the state of the art of weldbrazing, superplastic forming (SPF), superplastic forming and codiffusion bonding and superplastic forming and weldbrazing for titanium and the SPF of aluminum is discussed.

Description: Fatigue and fracture research on monolithic and laminated metals is discussed. The research concentrated on three areas: stress analyses of two and three dimensional cracked bodies, fatigue crack growth, and fracture toughness. Analytical methods were developed to predict fatigue crack growth and fracture strengths of cracked specimens. Such specimens represent typical aircraft structural details (such as cracks from holes). These specimens were subjected to simple constant amplitude loading and to more complex flight load histories. Test data from both in house tests and from the literature are used to substantiate the analytical methods. These analyses extended the theory of fracture mechanics to deal with fatigue crack growth and fracture of complex crack configurations that are typical of aircraft materials and structural details.